This invention relates to a rock drill boom structure and more particularly to such a structure which provides a simple and inexpensive mounting and rotation device for the boom.
Prior art drilling rigs with a boom structure of the above mentioned kind are very cumbersome in transport because of the overhanging length and weight of the boom structure. This is true even when the actual boom itself is telescopically extensible as is common in the art.
A boom structure according to the invention can, when mounted on a mobile carrier, be retracted into a transport position on the carrier. In the transport position it adds a comparatively short length to the carrier, and its center of gravity can be comparatively close to its mounting. This ensures easier and faster transport of the rig. One particular advantage is that the rig can be designed to fit within a mine shaft conveyance, such as a cage, without being dismounted. As a consequence, the transport of the rig into and down the mine and between the levels in the mine can be considerably facilitated.
The invention also provides a simple and inexpensive mounting and rotation device for the boom. The mounting device also permits for a simple drawing of the power lines through the boom.